CVE-2024-30602: Tenda FH1203 Buffer Overflow Vulnerability

CVE-2024-30602 Overview

CVE-2024-30602 is a stack overflow vulnerability affecting the Tenda FH1203 wireless router firmware version 2.0.1.6. The vulnerability exists in the schedStartTime parameter of the setSchedWifi function, which fails to properly validate input length before copying data to a fixed-size stack buffer. This classic buffer overflow condition can be exploited remotely over the network without authentication, potentially allowing attackers to execute arbitrary code or cause a denial of service on affected devices.

Critical Impact

This vulnerability allows unauthenticated remote attackers to potentially achieve complete device compromise through stack-based buffer overflow exploitation, enabling arbitrary code execution with full system privileges on the affected router.

Affected Products

• Tenda FH1203 Firmware version 2.0.1.6
• Tenda FH1203 Hardware Device
• Tenda FH1203 Wireless Router

Discovery Timeline

• 2024-03-28 - CVE-2024-30602 published to NVD
• 2025-03-13 - Last updated in NVD database

Technical Details for CVE-2024-30602

Vulnerability Analysis

The vulnerability resides within the setSchedWifi function of the Tenda FH1203 router firmware. This function is responsible for handling WiFi scheduling configuration requests. When processing the schedStartTime parameter, the function copies user-supplied input into a fixed-size buffer allocated on the stack without performing adequate bounds checking.

This vulnerability is classified under CWE-120 (Buffer Copy without Checking Size of Input), commonly known as a "Classic Buffer Overflow." The flaw can be triggered remotely over the network, requires no authentication or user interaction, and upon successful exploitation could lead to complete compromise of confidentiality, integrity, and availability of the device.

Root Cause

The root cause of this vulnerability is improper input validation in the setSchedWifi function. The function accepts the schedStartTime parameter from user input and copies it directly to a stack-allocated buffer without verifying that the input length does not exceed the buffer's capacity. This oversight allows an attacker to supply an oversized input value that overwrites adjacent memory on the stack, including critical control structures such as the function's return address.

Attack Vector

The attack can be executed remotely over the network. An attacker would craft a malicious HTTP request to the router's web management interface containing an oversized schedStartTime parameter value. When the vulnerable setSchedWifi function processes this request, the excessive input overflows the stack buffer, potentially overwriting the saved return address. By carefully crafting the overflow payload, an attacker can redirect program execution to arbitrary code, achieving remote code execution on the device.

The exploitation does not require any form of authentication, making any exposed Tenda FH1203 router running firmware version 2.0.1.6 vulnerable to attack from any network-accessible source.

For detailed technical analysis of this vulnerability, refer to the GitHub IoT Vulnerability Documentation.

Detection Methods for CVE-2024-30602

Indicators of Compromise

• Unusual HTTP requests to the router's web management interface with abnormally long schedStartTime parameter values
• Router instability, unexpected reboots, or unresponsive behavior indicating potential exploitation attempts
• Unexpected changes to router configuration or firmware settings
• Anomalous outbound network traffic from the router to unknown external IP addresses

Detection Strategies

• Monitor HTTP traffic to the router's management interface for requests containing the setSchedWifi endpoint with oversized parameter values
• Implement network intrusion detection rules to identify buffer overflow patterns targeting IoT devices
• Deploy network monitoring to detect abnormal traffic patterns originating from router devices
• Regularly audit router firmware versions to identify vulnerable devices in the environment

Monitoring Recommendations

• Enable logging on network firewalls and security appliances to capture traffic to and from IoT devices
• Implement network segmentation to isolate IoT devices from critical network infrastructure
• Deploy SentinelOne Singularity for IoT visibility and protection across connected devices
• Establish baseline behavior profiles for router devices to detect anomalous activity indicative of compromise

How to Mitigate CVE-2024-30602

Immediate Actions Required

• Restrict network access to the router's web management interface to trusted IP addresses only
• Disable remote management features if not required for operational purposes
• Place the affected router behind a firewall that blocks external access to the management interface
• Consider replacing the affected device with a router from a vendor that provides regular security updates

Patch Information

At the time of this writing, no vendor patch information is available in the CVE data. Tenda has not released an official security advisory or firmware update addressing this vulnerability. Users should monitor the Tenda support website for firmware updates and apply any security patches as soon as they become available.

Workarounds

• Disable the WiFi scheduling feature if not required, as this may prevent the vulnerable code path from being reached
• Implement access control lists (ACLs) on the router to restrict management interface access to trusted local IP addresses only
• Use a VPN or secure tunnel when remote management access is required
• Monitor network traffic for exploitation attempts using intrusion detection systems

# Example: Restrict management interface access (router-specific)
# Access router configuration and limit management access to local network only
# Disable WAN-side management access in router settings
# Enable MAC address filtering for additional access control